Method for treating oils



Patented Mar. 23, 1943 METHOD FOR TREATING OILS Albert B. Doran, LosAngeles, Calif., assignor to Dorex Corporation, Los Angeles, Calil'., acorporation of Nevada No Drawing. Application October 15, 1940,

Serial No. 361,257

9 Claims.

This invention relates to a method for treating oil, and relates moreparticularly to metallic manganites or permanganites having selectiveadsorptive properties for sulphur compounds and to a method relating tothe use of such compounds in the desulphurization of oils.

The presence of sulphur compounds is frequently regarded as detrimentalto the quality of various oils. For example, gasoline produced fromsulphur-containing petroleum may contain sulphur compounds which areinjurious from the standpoint oi obnoxious odor and also from thestandpoint of corrosion, particularly as due to the formation ofcorrosive acids during the process of combustion. Also, the presence ofsulphur compounds may tend to reduce the efficacy of antiknock compoundsadded to the gasoline. Sulphur compounds also constitute anobjectionable constituent in many other types of petroleum products, forinstance, kerosene, fuel oils, lubricating oils, and the like.

i No completely satisiactorymethod is available for the selectiveremoval of the sulphur-containing impurities. Many methods, such as thewell known sweetening or doctor treatment, make no attemptto remove thesulphur compounds but simply to convert them into less odorous form.

When the attempt is made to remove sulphur compounds by treatment withconventional refining agents, such as sulphuric acid, the necessaryrigorous treatment is such as to simultaneously result in thedegradation of many valuable constituents of the oil. This isparticularly true in the case of cracked gasoline which is subject tosubstantial loss in olefins and other valuable fuel constituents whenrigorously treated for sulphur reduction.

It is an object of the present invention to provide a compositionadapted to selectively adsorb sulphur-containing compounds and toprovide a method for its eflicacious use in the desulphurizat'ion ofoil.

anhydride, Mn2O3, is well known. By the termpermanganite I havereference to salts of permanganous acid, HzMnOs, corresponding to theanhydride, M11102. It will be noted that in the manganite the manganeseis'trivalent and that in permanganite the manganese is tetravalent. Themanganite and permanganite salts maybe either simple or complex,depending on the molal ratios of the metal and manganese. For ex--ample, I may employ silver manganite, AgMnOz, or I may employpoly-manganites having the generic formula Ag20.(Mn2Oa)n, in which n isa simple integer that can be as high as 10 or more. Similarly, I mayemploy silver permanganite in the normal form, AgzMnOs, or in the acidform, AgHMnOa, or in the complex poly-permanganite form, Agz0.(MnO2)1r,u again being an integer. The terms manganite and permanganiteuaredeemed generic to the various species, such as the normal, acid and polysalts.

Various methods known to the art may be employed .for the directmanufacture of the metallic manganites' and permanganites, but I findthat the best results are obtained by first synthesizing an alkali metalmanganite or permanganite and then converting the alkali metal salt intothe desired metallic salt by a process of base exchange such as willpresently be described: V The alkali metal manganites and permanganitesmay be variously produced. For example, it is known that when MI1(OH)2is oxidized in the presence of an alkali the brown substance producedcontains more or less alkali combined with the MnOz in the form ofalkali permanganite. Lime permanganites, such as CaO.MnO2 and CaO.2MnOzare produced in the Weldon manganese recovery process for themanufacture of chlorine, and such alkaline earth permanganites may alsobe used as intermediates in a manner similar to the alkalipermanganites. Alkali permanganites are also produced in certain instances during alkaline oxidation with manganate and permanganate.

The known methods for production of alkali manganites are somewhitesimilar, and may depend upon alkaline hydrolysis of a manganic salt'or-controlledoxidation or reduction of lower and ably' in alkalinemedia.

higher valenced manganese compounds, prefer- A particularly advantageousway-to obtain the alkali metal 'manganite is to fuse a mixture ofmanganese dioxide and caustic alkali as described in greater length inmy copending application entitled Catalysts and preparation, Serial No.361,258, filed October 15, 1940.

The alkali metal manganite or permanganite, preferably in powdered form,may be placed in an aqueous. solution of a water soluble salt ofthemetal which it is desired to associate with the manganite orpermanganite. Base exchange rapidly takes place between the solid andliquid phases with the result that the desired metal is fixed by themanganite or permanganite with simultaneous formation of an alkali metalsalt in the solution.

Thus, for example, a finely powdered potassium manganite may be stirredinto an aqueous solution containing silver nitrate in quantityapproximately equivalent to the alkali associated with the manganite. Ashort period of contact suffices to complete the base exchange and the'silver manganite, after washing with water and drying, is in suitableform for its use in desulphurization.

According to the method of preparation, a manganite, permanganite, ormixed manganite and permanganite salt may be obtained. Also, there mayfrequently be more or less uncombined manganese sesquioxide or dioxidein anhydrous or hydrated form. I may employ all of such mixtures asadsorbents, although in general the most active adsorbents are thosewhich contain a substantial content of the desulphurizing metal,typically silver.

While it may reasonably be assumed that the active silver (or othermetallics) constituent associated with the manganese, 'sesquioxide ordioxide in an insoluble form is actually present as a true manganite orpermanganite and properly termed as such, I do not wish to be bound byany theory as to the precise molecular structures involved, and wherereference is made to manganite or permanganite salts, I Wish only toimply that the metallic oxides and the manganese dioxide or sesquioxideare in some associated form, which form is characterized by itsinsolubility in water and its properties of selectively adsorbingsulphur compounds as herein described.

For the purpose of adsorbing sulphur the acidic manganese is preferablyassociated with a metal whose sulphide is highly insoluble, preferably,silver or copper. I find silver to be the best metal to employ, sincethe silver manganite and permanganite possess such high desulphurizingpower as to more than oifset any increased cost of reagents.

The process of desulphurization may be illustrated with respect to thespecific treatment of gasoline. By contacting a gasoline containingsulphur compounds with an adsorptive agent of the kind described,typically silver mianganite or permanganite, I may effect selectiveadsorption proceeding to the degreeof practically complete sulphurremoval provided that sufficient of the adsorptive material is employed.For most practical purposes it is sufiicienttoreduce the sulphur contentto within a tolerated or specified limit, and for such purposes arelatively small portion of the adsorptive agent generally suffices.

The adsorption is relatively rapid and in practice may be realized undervarious conditions. For example, the adsorbent in powdered form.

may be added to a batch of gasoline and maintained in suspension byagitation until the desired adsorption is complete and then removedsuitably by filtration.

Alternatively, the gasoline may be caused to flow as a continuous streamthrough a bed comprising sulphur adsorptive agents of the typedescribed. For this purpose the adsorptive agent may be bestmanufactured in formswhich' permit their aggregation as arelativelyporous bed, asbycompressmn intopellets or admixture into granular orporous supporting material.

Frequently it is advantageous to combine the sulphur adsorbent withconventional adsorbents such as clay, fullers earth, and the like, whichare efifective primarily on colored compounds and highly unsaturatedhydrocarbons. Suitable mixtures may be formed simply by admixture ofpowdered sulphur adsorbent and granular clay in the dry state.Preferably, the powdered sulphur adsorbent is mixed into wet plasticclay and the resulting mixture is then dried and ground to a suitablesize for percolation, contact filtration or the like,

The sulphur adsorbents of the type described may also be employed forvapor phase treatment of the gasoline or other oil. The gasoline may bevaporized and caused to flow through an adsorptive bed comprising thesulphur adsorbent, suitably at a temperature in the neighborhood of thedew point of the vaporous mixture. This aspect of my invention forms aparticularly advantageous adjunct to the vapor phase clay treatment ofcracked gasoline, in which connection there may be very convenientlyemployed fullers earth or similar clay in which the sulphur adsorbenthas been previously.iincorporated, for example, by the Wet methoddescribed above.

Mercaptans are very readily removed from gasoline by liquid or vaporphase treatments of the kind just described, to give sweet'gasoline ofundiminished or increased lead susceptibility. In addition by employingmore prolonged contact or a greater proportion of the sulphur adsorbentthe sulphur content may be reduced to, or below any value normallyspecified for commercial quality gasoline.

A very important feature of my invention is the regeneration of thespent sulphur adsorbent which in its spent condition comprises a layerof adsorbed sulphur compounds overlying the surface of the adsorbent insuch a manner as to mask its further activity. If desired this adsorbedsulphur-containing material may be removed by solvent extraction with arelatively powerful solvent such as aromatic hydrocarbons, alcohols, andthe like, but I find a more convenient and economic method ofregeneration consists merely in exposing-the spent adsorbent to theaction of air or other oxygen-containing gases at temperaturessufilcient to initiate and maintain the combustion of thesulphur-containing material. The temperatures necessary for thisregeneration are insufficient to harm the manganese adsorbent whichaccordingly may be used over and over again in a cycle involvingregeneration of. the kind described. Various means normally employed forthe roasting and regeneration of spent clays may be used to accomplishregeneration of the sulphur adsorbent as herein described.

It will be understood that the detafls of the above description areexemplary rather than limiting and it will be obvious to one skilled in.the art that various modifications of the described composition andprocess may be employed oil with an adsorptive agent containing acompound of an acidic oxide of manganese in which the valence of themanganese is not more than four witha metal whose sulfide is highlyinsoluble in said oil.

2. In the process of desulphurizing 0115 the step comprising contactinga sulfur-containing oil with a compound of an acidic oxide of manganesein which the valence of the manganese is not more than four with a metalwhose sulfide is highly insoluble in said oil.

3. In the process for desulphurizing oils the step comprising contactinga sulfur-containing oil with a compound of an acidic oxide of manganesein which the valence of the manganese is not more than four with a metalselected from the group consisting of silver and. copper.

4. In the process for desulphurizing oils the step comprising contactinga sulfur-containing oil with a compound of an acidic oxide of manganesein which the Valence of the manganese is not more than four with silver.

5. In the process for desulphurizing oils the step comprising contactinga sulfur-containing oil with a compound of an acidic oxide of manganesein which the valence of the manganese is not more than four with copper.

6. The method of desulfurizing oils comprising contacting said oil withan adsorptive agent including a compound of an acidic oxide of manganesein which the valence of the manganese is not more than four with a metalselected from the group consisting of silver and copper, recovering theadsorptive agent charged with sulfur compounds, and regenerating saidagent by removing the sulfur.

7. The method of desulfurizing oils comprising contacting said oil withan adsorptive agent including a compound of an acidic oxide of manganesein which th valence of the manganese is not more than four with a metalselected from the group consisting of silver and copper, recovering theadsorptive agent charged with sulfur compounds, regenerating said agentby heating in the presence of an oxygen-containing gas, and employingthe regenerated agent to similarly desulfurize further quantities ofoil.

8. The process of claim '7 in which the adsorptive agent is silvermanganite.

9. The process of claim 7 in which the adsorptive agent is silverpermanganite.

ALBERT B. DORAN.

